The present invention relates to an engine generator having an engine, a generator and a muffler protected by an engine cover.
For a so-called engine generator in which an engine and a generator that is driven by the engine are both arranged, the components, such as an engine, are mostly protected by a sound insulating cover. Such an engine generator requires openings as small as possible for sound insulation whereas those as large as possible for cooling the inside of an engine cover. To meet these contradictory requirements, most engine generators have an engine-driven cooling fan protected by an engine cover for circulating air taken thereinto for high cooling efficiency.
Japanese Unexamined-Patent Publication No. 11-36880 discloses an engine generator provided with a cooling fan for improving sound insulation and cooling efficiency. The engine generator has a generator, an engine, and a muffler aligned in this order and surrounded by ducts protected by a cover. A cooling air is introduced into the duct from the generator side.
In other words, the engine, the muffler, etc., are protected by both the ducts and the cover. Cooling is performed in the order from the generator that will generate heat of relatively low temperature to the engine and muffler that will generate heat of high temperature.
Sound insulation is improved by means of double structure of the ducts and cover. Moreover, the engine generator is cooled efficiently because of cooling in the above order.
However, due to such a double structure that covers an engine and a muffler, and moreover, covered with an engine cover, as disclosed, such an engine generator is disadvantageous in that the number of components and assembly steps increases, thus raising cost.
A purpose of the present invention is to provide an engine generator having a small number of components and exhibiting sound-insulation capability with high cooling efficiency.
The present invention provides an engine generator having an engine and a muffler driven by the engine, both protected by an engine cover, the engine cover having a double-wall structure of an outer wall that protects the engine generator, an inner wall that forms a space for containing the engine and used as a cooling-air passage through which the engine and the muffler are cooled, and a hollow inner space formed between the outer and the inner walls.